CD40 ligand (CD40L) (CD40L)

CD40 ligand (CD40L), also known as CD154 or TNFSF5, is a type II transmembrane protein belonging to the tumor necrosis factor (TNF) superfamily, primarily expressed on the surface of activated T lymphocytes [1]. It serves as a critical costimulatory molecule by binding to its receptor, CD40, which is constitutively expressed on antigen-presenting cells such as B cells, macrophages, and dendritic cells [2]. This interaction is fundamental for T-cell-dependent B-cell maturation, including isotype switching, somatic hypermutation, and the formation of long-lived memory B cells [1, 2]. Beyond B-cell help, CD40L signaling promotes the production of pro-inflammatory cytokines and the activation of vascular endothelial cells, linking adaptive immunity to chronic inflammation and atherosclerosis [2, 3]. Genetic deficiencies in CD40L lead to X-linked Hyper-IgM syndrome, characterized by severe immunodeficiency and a lack of germinal centers [1]. In therapeutic contexts, CD40L is a major target for treating autoimmune diseases like systemic lupus erythematosus (SLE) and preventing organ transplant rejection [4]. However, early clinical trials of anti-CD40L monoclonal antibodies were halted due to unexpected thromboembolic events caused by the activation of CD40L on platelets, leading to the development of next-generation inhibitors designed to avoid Fc-mediated platelet aggregation [3, 4]. Sources: [1] UniProt P29965; [2] PubMed PMID: 28213359; [3] PubMed PMID: 11069068; [4] ClinicalTrials.gov / DrugBank.

Other names

CD154Tumor necrosis factor ligand superfamily member 5TNFSF5T-cell antigen Gp39TNF-related activation proteinTRAPT-BAM

Inhibition of the CD40-CD40L costimulatory pathway by binding to the CD40 ligand and preventing its interaction with the CD40 receptor.